The disclosure relates generally to turbomachine bearing configurations, and more particularly, to turbomachine bearing configurations for limiting deflections and stresses during blade out events.
A variety of turbomachines, including engine fans, compressors, and turbines, include airfoils or blades in a balanced configurations around a shaft. Many of these turbomachines require that the machine demonstrate the ability to survive a blade failure at operational revolutions per minute (rpm) for some period of time or during a controlled shutdown period. Containment of high speed particles and limiting the failure of mounting attachments for the blades are important criteria for making it through these blade out events. In addition, limiting deflection of the shaft and preventing undue stress or failure in other parts of the gas turbine, such as the exhaust frame, that surround and position the shaft are also important. The configuration of the bearing between the shaft and the exhaust frame may be a relevant factor in limiting shaft deflection and resulting stresses in the exhaust frame and elsewhere. Ideally, blade loss should be limited to the initial failed or released blade. If the imbalance and resulting stresses become too great, loss of the entire turbomachine can result.
In some configurations, an exhaust frame surrounds a bearing that guides the shaft through the exhaust frame. The exhaust frame includes an inner barrel and outer barrel and connecting struts. During a blade out event, the imbalance from the remaining rotating blades in the turbomachine is translated through the shaft and into the bearing and exhaust frame. If those stresses become too great, deformation and failure of the bearing housing and/or the bolts holding the exhaust frame to the bearing housing can result, which may enable catastrophic deflection of the shaft.